Hydrosilylation of RN=CH Imino-Substituted Pyridines without a Catalyst

Article abstract of DOI:10.1002/chem.201604892

Treatment of the neutral pyridine-based ligands L¹–L³, bearing either one or two RN=CH imine moieties {where L¹ and L² are N,N-chelating ligands 2-(RN=CH)C₅H₄N (R=Ph (L¹) or R=2,4,6-Ph₃C₆H₂ (L²)) and L³ is the N,N,N-chelating ligand 2,6-(RN=CH)₂C₅H₃N (R=2,6-iPr₂C₆H₃)}, with HSiCl₃ yielded N→Si-coordinated silicon(IV) amides 2-{Cl₃SiN(R)CH₂}C₅H₄N (1, R=Ph; 2, R=2,4,6-Ph₃C₆H₂) and 2-{Cl₃SiN(R)CH₂}-6-(RN=CH)C₅H₄N (3, R=2,6-iPr₂C₆H₃). The organosilicon amides 1–3 are the products of spontaneous hydrosilylation of the RN=CH imine moiety induced by N→Si coordination of the proposed N,N-chelated chlorosilanes L¹→SiHCl₃ (1 a), L²→SiHCl₃ (2 a), and L³→SiHCl₃ (3 a). Furthermore, the reaction of L³ with an excess of HSiCl₃ provided the intramolecularly coordinated chlorosilicon diamide cyclo-{(C₅H₃N)-1,3-(CH₂NR)₂}SiCl₂ (4) (R=2,6-iPr₂C₆H₃) as the product of spontaneous reduction of both RN=CH imine moieties. The compounds have been characterized by NMR spectroscopy (1–4) and single-crystal X-ray diffraction analysis (1, 3, and 4). The mechanism of the hydrosilylation of the second RN=CH imine moiety in 3 by an excess of SiHCl₃ has also been studied. The experimental work is supplemented by DFT calculations.